1. Field of the Invention
The present invention relates to paint spray guns. More particularly, the present invention relates to a paint spray gun which includes a mounting clamp which allows rotatable movement of the gun body therein.
2. Prior Art
In conventional paint spray guns, a stream of paint under pressure is discharged from a relatively small orifice in a nozzle. At the same time, pressurized air is discharged radially into the stream, from an annular opening surrouding the nozzle, immediately adjacent the paint discharge orifice to atomize the stream of paint into a spray of fine droplets. The spray thus moves away from the gun in an expanding conical pattern whose apex is at the nozzle.
It is frequently preferred to modify the circular cross-section of the normal conical spray pattern so as to transform the cross-section into a narrowed and elongated generally elliptically shaped cross-section, so that the spray pattern more closely resembles a flat-sided fan or a parabola than a cone when viewed from the side. This modification of the spray pattern allows for more efficient and controlled painting than is obtainable with a conical spray.
In many prior art spray guns, fanning of the spray pattern is often accomplished by providing an air cap at the front section of the gun. The air cap normally has a pair of substantially diametrically opposed fanning air passageways formed therein which terminate at outlets which are spaced outwardly from opposing sides of the annular air discharge opening. The fanning air passageways are oriented to direct air jets toward opposite sides of the spray pattern at a location spaced a short distance forward of the nozzle orifice. These jets have the effect of flattening the sides of the conical spray pattern. At any given distance from the nozzle, this flattening effect transforms the normally circular cross-section of the spray pattern into a generally elliptically shaped cross-section whose major axis is somewhat greater than the original cone diameter and whose minor axis is somewhat less than the original cone diameter. This "flatness" of the spray pattern will increase with an increase in the pressure at which are expelled from the fanning ports. A brief review of some previously published patents on paint spray guns follows.
Carr, U.S. Pat. No. 2,553,401 discloses an air-actuated paint spray gun of the general type described above. The gun of Carr uses only a single source of compressed air to atomize the paint issuing from the nozzle as well as to actuate a piston which moves to overcome a restraining spring and to displace a needle out of the nozzle orifice to release the flow of paint. Because a single source of air is used to perform both of these functions in Carr, a "lost motion" connection is used between the piston and the needle which restricts the nozzle orifice. However, this type of connection requires a separate spring to bias the needle into a normally closed position even when the piston has begun movement within the body of the gun, and does not allow for adjustment of the pressure to the fanning outlets independent of the pressure which turns the gun on and off. Thus, fine control of the shape of the spray pattern could be difficult with the design of Carr. In addition, the spray gun of Carr uses a fairly complicated venting system to release air from behind the piston, the venting system involving a rotating cam and a spring-loaded valve in communication with the piston chamber.
U.S. Pat. No. 4,744,518 to Toth, who is the present applicant, discloses a manually actuated paint spray gun which is also of the general type described above, and which further has a mechanically operated air cylinder which is movable within the gun to obstruct or not to obstruct the fanning air passageways in the air cap. Movement of the air cylinder with respect to the air cap allows for control of the pressure leaving the fanning ports, and thus allows a user of the gun to control the shape of the spray pattern.